Range finder



Allg. 21, 1945. E B, HAMMOND ET A| 2,382,991

RANGE FINDER Filed Sept. 17, 1942 zum FIG. 7

M oRNEY.

l Patented Aug. 21, 1945 l Animation; sestembr 17, A135,12, s

@"Thiszinvention relatesto an critical instrument l and method bywhichan estimatedrange of "a distant `object of atl least one known"` dimension may be determined Vby anobserver. I One `of the `featuresof .the invention resides `in the use in the optical system `for the range filnder of la reticle formed tolin'clude a' plurality` offlcone centric 'circles whose respective Ldameters are in` dicative of different ranges.` I Il i f Another feature of the "inventioncons'ists in the inclusion inthe optical system of the' range nder of sa lens which produces' an enlargedimage` fof the `defined typeflof reticlearid also Iincludes means for superimposing theenlarged imageof; the reticle onthefvlewed object.` I 1' I l I ifStillafurther feature of `the inventionresldes in the employment inthe range finder cfa num-` ber of individualf-reticles'eachof which is formed of ai. plurality oit` range indications, the" `reticles being arrangedin `spared J relation' on a movable plate l and I respectively vcorresponding' to various differentikn'own1 dimensions fof Lthe objets to be Observedw` L" "j i Thefrange nder of the 'present invention` is particularly adapted for use in estimatingthe range of an airplane 'with a knowni'wing sbread orv `fuselage dhnerisicm` although 'obviously the samerislnot'limted-to use for" target`s" ofi this Character. t n' fl 'i 'l` Othel- .features and' structural'details of the inventlonirwill beapparent from the following'description `When read in connection' with lthe accompanyingdrawing;'wherein':` 1 C f w I I Fig; l .isla front 'elevationof a range `mier'con-A struetedfin' accordance'with the :present invenubn 'w I f I l y Fig. 2 is a side elevation of therangeinder with thecasingthereof:shownlrrsectlon.

reticle employedin the improvedfrangelinder.. -f Figffl isa-detail end elevation of'gth'e reticle holding'part.' 't` I y i IFigJ`5 is'a detailviewshowing a portion ofthe l formj of 'reticle in which"the plate is'translucentk and the `circles thereon are'traiisbarent.

"sigle-is a detail view of ai modified form lor I Figxf? is `a `diagrammatic view` illustratingyt'he principleofoperation' ofthe improved lrange finder; C

with reference to Figs. iarida partenariati the drawing', lthe improvedirange iinderis shown in the form Vof a box-like CaSingJdhaving front and rear Windows, respectively indicated at Il and I2 whlchare situated 1n oppositely disposed nel No. 45ans 101.8115423) mounted exteriorlyof the casing, `the samebeine I movable to a positioninrwhichsthelsame covers the Window `II ifde'sired.` In use, the Joox'casing 5 may be held in the hand of the observer or may be suitably mounted `on awtripodwor `other stand. The observer positions thebox 4casingnso that the object ortarget to be cbservedfisoseen directly through the respectivewindowswlzandlU ofthe l instrument. As shown inligffl the field of view mi; of the observer is indicated by the: line I4. The opticalssystem of the range ,nderfconsequently includes means throughwhich a distant object is viewed. 'Y I i `15 `The interior of: th'ebox-like casing includes'an Elf: `optical means for superimposing" an imageoft a reticle,. which is hereafter 4more panjticularlyy de- I scribed; in the fielctoi view that the observer'has ofi-the object. This means `in the-p1esent in-v 20, stance"`is shown inthe formvofan angularlyrposi- @il tioned transparent glassiplatel.` "Plate I5 is ldisL` I pbsed` in t 45 I relation with respect to I the `axis of t sight ofthe observer through thewindows I2 and I I. Retaining' arms `are provided within the 2.5 box casing for:`flxedly mounting the. inelinedvplate' in position.` Itwill be understoodthatinasmuch aslpiate I5 `is I clear` `glassit 1does not `obstuctnthe t observers view of the *object* or. target. f Further included `in the optical 'system of the improved i0 range flnderzisa lens Iymountedintheshelfull Within the casingl which produces anenlarge'd image ofthereticle." "o I.

I Withinthe box casing IDandbelow theshelf Il is` situated i a movable plate `I 81,1fFig. `3, having; a

A number of individual reticles as' lindicatediat I'B, eight in thepresent instanceyeach o'f'vwhichds formed ofa plurality lofrangeindicating circles. With particularrefercnce to Figs-` 4"andx5 the disci-shaped retlcleplate lis' suitably mounted 40 within an annular member 20th/hose peripheral surfaceincludes 'rounded indentationsl; 2l 4and gear teeth`22.-` Member `llincludes'spokes23; a hub 24 `and.V shaft 25`- andis rotatablynmounted jbe'- tween `two spaced bearings of suitable cons1-.ruc-A tion situatedgin the respective extending-arms of a. bifurcatedpieceZS which' is faced to the' in'teido'r sidewall ofthe casing; The mechanism provided v for setting the plate I8. ,to position a'clx-siiedreti-t` cle I9 inthe opticalsystemwcffthefrangeflncle includes a yieldably held#` detent 21,"situated in `the fixed piece 26, Whose` end engages'the'respective spaced indentations ZIJ in. the annular membert` to perform "this function. L 'It will"` be understood that only one of 'the reticleson the plate I8' is includedrin, the optical fsystemabtfthe"rang 1 wens ofihe'cesing; Angie elfen; lads encreur y nder at any given time. Each reticle I9 when properly positioned is included in the primary focal plane of the lens I6; In accordance with the teaching of the invention the respective reticles are formed to include a plurality of concentric circles Whose respective diameters are indicative of dilerent ranges. The annular member is turned by the observer through ymeans of a knob 28 and gear 29 which meshes with the gear.

teeth "22. The optical system of the instrument also includes a light source such as bulb 30, theY light of which is directed upon the reticle through a diffusing glass 3|. y

With reference to Fig, 5, the plate I8 isshown as constructed of glass having a translucentvcovering or emulsied surface 32 and the respective circles 33 thereon, four being shown, `for each -construction and many apparently widely different4 embodiments of this invention could be of the reticles are formed by leaving transparent.,-v

areas in the glass. In the type of reticle plate shown 'in Fig. 6, the plate I8 is formedoftransparent glass, and the respective concentric circles for a. particular reticle are provided by the relatively heavy opaque 4lines thereon indicated at 34. 1

Each of the respective reticles I9` are designed for use in viewing an object or target of at least one' known dimension,` for example the sm'all reticle on the plate I8 may be employed in de-` termining the range from the observerof an airplane whose wing spread or fuselage dimension isA thirty feet. The other separate reticles are designed for use in the system when ythe known dimension of the object is respectivelyfeithe'r forty, nity, sixty, seventy,y eighty, ninety or one hundred feet'. With the proper reticle in use for a given object, the superimposed image of the circles of the reticle with respect toi the `object is viewed by the observer. Acomparison isthen made without departing from the scope thereof,

.itis intended thatall matter contained in the above descriptionor shown in the accompanying fdrawingshallfbeinterpreted as illustrative and not in a limiting sense.

What isclaimed is:

1.,Arange finder having an optical system including means through which a distant object of one knoWnfdimension-.is Viewed, a movable plate having a' number of vindividual reticles re spectively corresponding to' particular'4 object dimensions, each of ywhich is `formed of a plurality of range indicating circles, mechanism.for setting said plate to position a desired reticle in the optical system ofthe `range finder, and optical means for superimposing an enlarged image of the desired reticle on the viewed object.

2. A range finder as claimed in claim l, which further includes means for indicating ItoA an observer the particular reticle positioned in the optical system of the range nder. n

3. In a range iinder having an optical' system f including means through whichv anV object may made by the observer of the width of the'known dimension of the object when positionedv dia'- metrically vwith relation to the ci-rcleson which the object is superimposed. Inasmuch as the diametrlcal size of the outside circle of the reticle is designed to give a Vrange indicationof five hundred yards, the second circle of one thousand yards, the third circle of fifteen hundred yards, and the inner rcircle of two thousand yards, the observed size of the object with relation to the circles whenthe same are properly related 'enables the observer to closely estimate the actual range of the object from the instrument.v t

To provide a means for indicating to the observer the particular reticle positioned vin the optical system of the range finder, numerical indications 35 of the object dimensions for eachreticle I9 are included on the reticle plate I8. As'will be observed in Fig. 7, the secondary focal length of the lens I6 is such as to provide anenlarge'd image of the reticle to iocuswithin the leldof view of the observer. In arriving at the sizeof the respective reticle circles, the same 'were calculated in accordance with the followingfequation, f/ d=R/ T. D. where f is the primary focal length of the lens I6', d is the diameterof one of the circles of a particular reticlev I9, AR is the range of the object from the observerA which is substantially the secondary focal length 4of the lens I6 and T. D.'corresponds to the actual siz'e of therknown target or object dimension.v As shown in Fig. 7, the enlarged image of a given be viewed by an observer, a plurality of'reticles each formed'of a plurality of rconcentric range indicating circles-oil graded sizes, the reticles respectively correspondingto particular object dimensions, Aopticalcmeans selectively associable with one of said reticles for'supermposing an image of the associated'reticle upon the image of the viewed object, and manual meansl for associating kany\.desired reticle with said optical means. f 1 f vli. In a range finder having an optical" system includingmeans throughl which an object may be'viewed by an observer, a movable plate having a plurality of individual reticles each formed circles of graded sizes, the reticles respectively corresponding to 4particular' object dimensions, manually operable ;mechanism for setting said plate to Vposition a desired reticle in the optical system of fthe range finder, and optical means for superimposing an image of the desired reticle on the image ofthe viewed object.

5. In a range finder having an optical system including means through which an object may be viewed-byfan observer, a movable plate having a plurality of individual reticles ofgraded sizes re` spectively corresponding to particular` target dimensions, each reticle being formed of a pluraliy of concentric range indicating circles, said plate having a series of detents spaced circumferentially thereon, a spring-held member arranged to cooperate with said detents to tend to maintain saidy plate in a position such that thedesired reticle lies in the optical system of the range finder, manually operable mechanism for setting EDMUNDB. HAMMOND. DAVID J. CAMPBELL. 

